Bidder Support in Multi-item Multi-unit Continuous Combinatorial Auctions: A Unifying Theoretical Framework

Combinatorial auctions have seen limited applications in large-scale consumer-oriented marketplaces, partly due to the substantial complexity to keep track of auction status and formulate informed bidding strategies. We study the bidder support problem for the general multi-item multi-unit (MIMU) combinatorial auctions, where multiple heterogeneous items are being auctioned and multiple homogeneous units are available for each item. Under two prevalent bidding languages (OR bidding and XOR bidding), we derive theoretical results and design efficient algorithmic procedures to calculate important bidder support information, such as the winning bids of an auction and the minimum bidding value for a bid to win an auction either immediately or potentially in the future. Our results unify the theoretical insights on bidder support problem for different bidding languages as well as different special cases of general MIMU auctions, namely the single-item multi-unit (SIMU) auctions and the multi-item single-unit (MISU) auctions. We also consider auctions with additional bidding constraints, including batch-based combinatorial auctions and hierarchical combinatorial auctions, as well as the combinatorial reverse auctions, all of which have relevant practical applications (e.g., industrial procurements). Our results can be readily extended to solve the bidder support problems in these auction mechanisms.

Slow Firing Single Units Are Essential for Optimal Decoding of Silent Speech

Summary The motivation of someone who is locked-in, that is, paralyzed and mute, is to find relief for their loss of function. The data presented in this report is part of an attempt to restore one of those lost functions, namely, speech. An essential feature of the development of a speech prosthetic is optimal decoding of patterns of recorded neural signals during silent or covert speech, that is, speaking ‘inside the head’ with no audible output due to the paralysis of the articulators. The aim of this paper is to illustrate the importance of both fast and slow single unit firings recorded from an individual with locked-in syndrome and from an intact participant speaking silently. Long duration electrodes were implanted in the motor speech cortex for up to 13 years in the locked-in participant. The data herein provide evidence that slow firing single units are essential for optimal decoding accuracy. Additional evidence indicates that slow firing single units can be conditioned in the locked-in participant five years after implantation, further supporting their role in decoding.

A Novel Approach for Fire Safety

Liquids and solvents in industrial products produce flammable vapor which, when mixed with air, can ignite or explode. The ease by which those liquids produce flammable vapors depends on their flashpoints which allow them to be categorized according to the fire hazard they exhibit in their normal use. In this chapter, a novel approach for the classification of liquids is proposed. The proposed approach relies on the use of a vector network analyzer, a patch antenna, and a group of classifiers. In this study, random forest and REPTree algorithms are preferred as classifers. As proven in the study, random forest algorithm can provide higher accuracy than REPTree algorithm in the classification of hazardous liquids. A prototype system is currently under development in order to integrate the components of the proposed approach into a single unit. It is expected that the prototype system will quickly and reliable make a non-contact classification of liquids in different kinds of bottles.

Permitted speed decision of single-unit trucks with emergency braking maneuver on horizontal curves under rainy weather

Under adverse weather conditions, visibility and the available pavement friction are reduced. The improper selection of speed on curved road sections leads to an unreasonable distribution of longitudinal and lateral friction, which is likely to cause rear-end collisions and lateral instability accidents. This study considers the combined braking and turning maneuvers to obtain the permitted vehicle speed under rainy conditions. First, a braking distance computation model was established by simplifying the relationship curve between brake pedal force, vehicle braking deceleration, and braking time. Different from the visibility commonly used in the meteorological field, this paper defines "driver’s sight distance based on real road scenarios" as a threshold to measure the longitudinal safety of the vehicle. Furthermore, the lateral friction and rollover margin is defined to characterize the vehicle’s lateral stability. The corresponding relationship between rainfall intensity-water film thickness-road friction is established to better predict the safe speed based on the information issued by the weather station. It should be noted that since the road friction factor of the wet pavement not only determined the safe vehicle speed but also be determined by the vehicle speed, so we adopt Ferrari’s method to solve the quartic equation about permitted vehicle speed. Finally, the braking and turning maneuvers are considered comprehensively based on the principle of friction ellipse. The results of the TruckSim simulation show that for a single-unit truck, running at the computed permitted speed, both lateral and longitudinal stability meet the requirements. The proposed permitted vehicle speed model on horizontal curves can provide driving guidance for drivers on curves under rainy weather or as a decision-making basis for road managers.

High density single-unit human cortical recordings using the Neuropixels probe

A fundamental unit of neural computation is the action potential. While significant advances have been made in the ability to sample action potentials of large numbers of individual neurons in animal models, translation of these methodologies to humans has been lacking due to clinical time constraints, electrical noise in the operating room, and reliability of the methodology. Here we present a reliable method for intraoperative recording of dozens of neurons in humans using the Neuropixels probe, yielding up to ~100 simultaneously-recorded single-units (n=596 across 11 recordings in 8 participants). Most single-units were active within 1 minute of reaching target depth, compatible with clinical time constraints. Cell pairs active close in time were spatially closer in most recordings, demonstrating the power to resolve complex cortical dynamics. Altogether, this approach provides access to population single-unit activity across the depth of human neocortex at scales previously only accessible in animal models.

Limberg flap as a Primary Treatment for Pilonidal Sinus at Nepal Mediciti Hospital: A Single Unit Experience

INTRODUCTION: Pilonidal Sinus is a common condition with estimated incidence of 260 per million population with more male predilection and is often seen in sacrococcygeal area but has also been described in other areas with hair. The Limberg rhomboid flap was designed by Limberg in 1946 for the closure of a sixty degree rhombus shaped defect with a transposition flap. We would like to share our single unit experience of Rhomboid Limberg flap for Pilonidal sinus in our hospital. METHODS: This is an ongoing prospective descriptive study in the Department of General Surgery and Digestive Diseases of Nepal Mediciti Hospital from October 2018. The demographic of the patients, presenting symptoms, duration of symptoms and previous interventions are recorded and the Rhomboid Limberg flap surgery is done under regional or general anesthesia in prone position. The patient is given intravenous antibiotic and is instructed to sleep laterally or in prone position for 24 hours. The dressing is removed and the wound is inspected for flap status in the next morning. The patient is discharged on 1st post-operative day on oral antibiotics for 7 days and is followed on 7th post-operative day for removal of suction drain and alternate sutures in the skin and remaining sutures are removed on 10th post-operative day. RESULTS: We have done 28 cases of Limberg flap for Pilonidal Sinus from October 2018 to December 2020 of which 24 were male patients. None of our patients had flap necrosis. One patient presented with accidental removal of suction drain on 5th postoperative day, however he didn’t develop any wound related complication. One patient had superficial wound dehiscence on 10th post-operative day which healed on its own with dressing. One patient developed seroma from 5th postoperative and was managed with dressing and antibiotics and it healed in 2 weeks. None of our patients have developed recurrence and their wounds have healed satisfactorily with minimal scarring and pain. All the patients were able to resume their regular activities within 21 days. All except 2 patients were satisfied with cosmetic outcome. CONCLUSION: The Limberg flap is ideal treatment for pilonidal sinus with minimal postoperative pain, short hospital stay, few complications, rapid return to normal activities, good cosmesis, and a low recurrence rate with short learning curve for young surgeons. Hence, Limberg flap should be routinely used as primary treatment for pilonidal sinus.